This invention relates to face valve apparatus in general, and relates particularly to face valve apparatus incorporated in high speed continuous motion equipment for decorating beverage cans.
Today it is not unusual for continuous motion high speed apparatus to decorate 1,500 beverage cans per minute. Examples of this type of apparatus are disclosed in U.S. Pat. Nos. 3,766,851, 5,111,742 and 5,183,145. U.S. Pat. No. 3,766,851 issued Oct. 23, 1973 to E. Sirvet, J. Skrypek and E. Whelan for a Continuous Can Printer and Handling Apparatus, U.S. Pat. No. 5,111,742 issued May 12, 1992 to R. DiDonato and E. Sirvet for A Mandrel Trip Subassembly For Continuous Motion Decorators, and U.S. Pat. No. 5,183,145 issued Feb. 2, 1993 to R. Williams, E. Sirvet and R. Gabel for Apparatus and Method For Automatically Positioning Valve Means Controlling the Application of Pressurized Air to Mandrels on a Rotating Carrier.
In such continuous motion decorators, undecorated cans are loaded on mandrels that are mounted on a continuously rotating mandrel wheel near the periphery thereof. For each mandrel, vacuum or high pressure air is applied thereto for selected angular positions thereof. That is, vacuum is applied to load a can on the mandrel and to hold the can on the mandrel while decorations are applied to the can and varnish is applied over the decorations. High pressure air is applied to unload a can from a mandrel either after varnish is applied or before decorations can be applied when misloading of a can is detected.
To control the application of vacuum and high pressure air to the mandrel and obtain the foregoing operation, it has been found to be convenient to utilize face valve apparatus having a minimum of four relatively stationary stations that interface with a single continuously rotating ring shaped plate having a plurality of inlet ports that extend to a flat face thereof, with such face being perpendicular to the rotational axis for the plate. Conduits on the mandrel wheel connect each of the inlet ports to an individual one of the mandrels. Each of the stationary stations includes an outlet port that is defined by a wear pad which is biased against the face. Since the pad material is softer than the face material and the face is rotating at high speed, the pads are subjected to wear and must be replaced periodically.
In the prior art, replacement of even a single pad was a time consuming operation because all of the stationary stations were mounted on a common support plate which had to be dismounted from the machine frame in order to gain access to a damaged or worn pad to replace same. Further, in order to reduce the relative speed between the face of the rotating plate and the stationary wear pads engaged therewith, the latter were positioned relatively close to the rotational axis of the rotating plate. Because of this, the stationary stations were closely grouped in a confined area of the decorator. Even though somewhat flexible hoses are used to feed working air (air pressurized either substantially above or below ambient) to the stationary stations, because the hoses were close together, they formed a relatively stiff group of hoses. As a result, to gain access to a worn pad it was also necessary to detach and reconnect many, if not all, attachments between the hoses and the stations.